A multi-mode heat recovery system and method of controlling the same

Abstract

The present application relates to the technical field of heat recovery, and discloses a multi-mode heat recovery system and a control method thereof. The system comprises a double-working-condition main machine, an ice storage device, an ice melting plate exchanger, a single refrigeration unit, a total heat recovery heat pump unit, a heat pump unit, a domestic hot water tank, a cooling tower group, an ethylene glycol constant pressure supplementing device, a constant pressure water supplementing device, various circulating pumps (ethylene glycol pump, chilled water pump, cooling water pump, domestic hot water pump, heating circulating pump, etc.), a valve group, a pipeline system, a central group control system, sensors and control cables, etc. The system has multiple waste heat extraction modes, can recover waste heat from chilled water or cooling water alone, or simultaneously from both, effectively overcoming the problem of unstable heat recovery caused by waste heat end load fluctuation or intermittent operation in traditional systems. The system can continuously and reliably meet the demand for domestic hot water and heating, realize uninterrupted stable operation for 24 hours a year, and has good economic efficiency and operation reliability.

Description

Technical Field

[0001] This invention relates to the field of heat recovery technology, specifically to a multi-mode heat recovery system and its control method. Background Technology

[0002] In recent years, the excessive consumption of traditional fossil fuels has led to soaring energy prices. At the same time, international agreements such as the Paris Agreement have put forward clear requirements for greenhouse gas emission reduction. Traditional technology fields with high energy consumption and high carbon emissions have become key areas for transformation, among which the energy utilization issues in the industrial and building sectors are particularly prominent.

[0003] In industrial settings such as pharmaceutical parks, chip parks, and data centers, production processes require the absorption of waste heat from production lines or indoor spaces through chilled water systems 24 / 7. This waste heat is then transferred to the cooling water system via chiller condensers and subsequently discharged directly outdoors through cooling towers and other equipment. In contrast, in residential buildings such as offices, homes, apartments, and hotels, there is a demand for heating in winter and a demand for domestic hot water throughout the year. There is a clear mismatch between the availability of waste heat and energy demand between these two types of settings. Current technologies for integrating industrial waste heat treatment with civilian energy supply still face several unresolved technical challenges: First, the mainstream method for treating waste heat generated in industrial settings is through cooling towers. This method fails to effectively utilize the waste heat, and according to the reverse Carnot cycle principle, treating this waste heat requires additional electricity, necessitates the installation of cooling towers of appropriate scale, and evaporates a significant amount of water. This approach has considerable room for improvement in energy efficiency and water conservation. Second, some existing technologies attempt to recover heat from chilled water or cooling water systems, but these heat recovery methods are limited, often relying on a single system. The existing heat recovery technologies are mostly designed around the time when waste heat is generated. However, they do not have effective solutions for situations where waste heat supply may be insufficient or interrupted during off-peak hours (such as when production lines are partially or completely shut down at night or during low-load winter periods). Furthermore, the heating and domestic hot water supply of civil buildings mostly rely on traditional energy sources, and a stable connection mechanism has not yet been established with the waste heat resources of surrounding industrial settings. Therefore, a multi-mode heat recovery system and its control method are proposed to solve the above problems. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a multi-mode heat recovery system and its control method, which has the advantages of being able to extract waste heat from chilled water alone, or from cooling water alone, and in some modes, even from both chilled water and cooling water simultaneously. This solves the problems of existing heat recovery methods being too singular, having insufficient waste heat capacity, and being unstable.

[0005] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A multi-mode heat recovery system, including a dual-condition main unit, an ice storage device, an ice-melting plate heat exchanger, a single refrigeration unit, a total heat recovery heat pump unit, a heat pump unit, a domestic hot water tank, a cooling tower group, an ethylene glycol constant pressure replenishment device, a constant pressure water replenishment device, an ethylene glycol pump, an external network ice-melting pump, a first chilled water circulation pump, a second chilled water circulation pump, a third chilled water circulation pump, a domestic hot water circulation pump, a domestic hot water pressurization pump, a heating circulation pump, a first cooling water circulation pump, a second cooling water circulation pump, a third cooling water circulation pump, a fourth cooling water circulation pump, multiple valves, ethylene glycol pipes, chilled water pipes, heating hot water pipes, domestic hot water pipes, domestic hot water heating circulation pipes, cooling water pipes, users who use domestic hot water year-round for cooling in summer and heating in winter, users who use domestic hot water year-round for cooling, a central group control system, and control cables; The dual-condition main unit, ice storage device, and ice melting plate heat exchanger form an ethylene glycol circulation loop through ethylene glycol pipes; the single refrigeration unit, total heat recovery heat pump unit, and heat pump unit form a chilled water circulation loop with users who use cooling in summer, heating in winter, and domestic hot water and cooling throughout the year through chilled water pipes, and form a cooling water circulation loop with the cooling tower group through cooling water pipes. The domestic hot water tank is connected to the domestic hot water booster pump via a domestic hot water pipe, and is connected to the domestic hot water circulation pump and the total heat recovery heat pump unit in sequence via a domestic hot water heating circulation pipe, and then back to the domestic hot water tank to form a domestic hot water heating circulation loop. The domestic hot water users who use cold water in summer and heating water in winter and domestic hot water all year round are connected to the heating circulation pump and the heat pump unit via heating hot water pipe. The ethylene glycol constant pressure replenishment device is connected to the ethylene glycol pipe, and the constant pressure water replenishment device is connected to the chilled water pipe; Multiple valves are respectively installed at the nodes of the ethylene glycol pipe, chilled water pipe, heating hot water pipe, domestic hot water pipe, domestic hot water heating circulation pipe, and cooling water pipe; The ethylene glycol pump is installed on the ethylene glycol pipe, and the external network ice-melting pump is installed between the ice-melting plate heat exchanger and the chilled water pipe. The ethylene glycol side of the ice-melting plate heat exchanger is connected to the ethylene glycol pipe, and the chilled water side is connected to the chilled water pipe. The central group control system is electrically connected via control cables to the dual-mode main unit, ice storage device, ice melting plate heat exchanger, single refrigeration unit, total heat recovery heat pump unit, heat pump unit, cooling tower group, ethylene glycol constant pressure replenishment device, constant pressure water replenishment device, ethylene glycol pump, external network ice melting pump, first chilled water circulation pump, second chilled water circulation pump, third chilled water circulation pump, domestic hot water circulation pump, domestic hot water booster pump, heating circulation pump, first cooling water circulation pump, second cooling water circulation pump, third cooling water circulation pump, fourth cooling water circulation pump, multiple valves, heat meter, flow meter and various sensors.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, the dual-condition main unit, single refrigeration unit, and heat pump unit are each equipped with a condenser and an evaporator on their inner side; the total heat recovery heat pump unit is equipped with two condensers and one evaporator on its inner side, and the two condensers on the inner side of the total heat recovery heat pump unit are independent heat exchange chambers.

[0008] Furthermore, the central group control system can adopt programmable logic control or distributed control system, and the central group control system has an embedded load forecasting model. The load forecasting model is built based on the waste heat load value, downstream user energy demand, outdoor temperature value and real-time electricity price of the day. The central group control system also has a self-learning function, which is used to correct the load forecasting model according to the system's historical operating data.

[0009] Furthermore, the first chilled water circulation pump is installed between the single refrigeration unit and the chilled water pipe; the second chilled water circulation pump is installed between the total heat recovery heat pump unit and the chilled water pipe; and the third chilled water circulation pump is installed between the heat pump unit and the chilled water pipe.

[0010] Furthermore, the outlet of the domestic hot water tank is divided into two paths: one path is connected to the domestic hot water booster pump through a domestic hot water pipe, and the outlet of the domestic hot water booster pump is connected to the domestic hot water network of users who use domestic hot water for cooling in summer, heating in winter, and domestic hot water all year round; the other path is connected to the inlet of the domestic hot water circulation pump through a domestic hot water heating circulation pipe, forming a domestic hot water heating circulation loop.

[0011] Furthermore, the cooling tower group has a modular structure. Each module of the cooling tower group is connected to the first cooling water circulation pump, the second cooling water circulation pump, the third cooling water circulation pump, and the fourth cooling water circulation pump, respectively. Each module is electrically connected to the central group control system through a control cable and can be started and stopped independently.

[0012] A control method for a multi-mode heat recovery system includes the following steps: S1: The central group control system collects outdoor ambient temperature TW, domestic hot water hourly temperature T, heating user indoor hourly temperature TN, and the real-time electricity price of the day in real time; it reads the hourly cooling load value QL of upstream cooling users, the hourly domestic hot water load value QRS of downstream users, and the hourly heating load value QN of downstream users from the load prediction model. S2: The central group control system calls the load prediction model based on real-time data to determine the operating condition that the system should enter: when the sliding average outdoor temperature for 5 consecutive days is ≥22℃, it enters the summer operating condition; when the sliding average outdoor temperature for 5 consecutive days is ≤10℃, it enters the winter operating condition; when the sliding average outdoor temperature for 5 consecutive days is between 10℃ and 22℃, it enters the transitional season operating condition. S3: The central group control system selects the corresponding operating mode and issues control commands based on the current operating conditions and real-time electricity price to control the start-up, shutdown and opening adjustment of various equipment and valves; S4: During system operation, the central group control system collects actual load data in real time, corrects the working status of the system, equipment, and valves, or switches modes; at the same time, it enters the actual operating data into the historical database through the "self-learning" function and updates the load prediction model.

[0013] Furthermore, the control logic for the "summer operating condition" in step S3 includes: During off-peak electricity hours: The dual-mode unit enters ice storage mode; if the hourly temperature of domestic hot water T < the set target temperature TS, and the hourly cooling load QL of the user ≥ the downstream user's domestic hot water load QRS: the total heat recovery heat pump unit is started first, entering the main heating and secondary cooling mode; if this mode cannot meet the user's cooling demand, the single refrigeration unit cooling mode and the heat pump unit cooling mode are started in sequence to supplement the cooling capacity; if the hourly temperature of domestic hot water T < the set target temperature TS, and the hourly cooling load QL of the user ≥ the downstream user's domestic hot water load QRS: the total heat recovery heat pump unit is started, entering the simple heating mode of recovering cooling water heat; at the same time, according to the user's cooling demand, the single refrigeration unit cooling mode and the heat pump unit cooling mode are started in sequence to supplement the cooling capacity; if the hourly temperature of domestic hot water T ≥ the set target temperature TS: according to the user's cooling demand, the single refrigeration unit cooling mode is started first, and then according to the increase in cooling load, the total heat recovery heat pump unit simple cooling mode and the heat pump unit simple cooling mode are started in sequence to supplement the cooling capacity. During Pinggu electricity pricing periods: If the hourly temperature of domestic hot water T < the set target temperature TS: the total heat recovery heat pump unit will be activated first, entering the main heating and secondary cooling mode; if the cooling capacity is insufficient, the single cooling unit will be activated in cooling mode, the heat pump unit in simple cooling mode, the dual-mode main unit in cooling mode, and the dual-mode main unit + ice melting combined cooling mode to supplement the cooling capacity in sequence; if the hourly temperature of domestic hot water T ≥ the set target temperature TS: according to the user's cooling demand, the single cooling unit will be activated first; if the cooling capacity is insufficient, the total heat recovery heat pump unit in simple cooling mode, the heat pump unit in simple cooling mode, the dual-mode main unit in cooling mode, and the dual-mode main unit + ice melting combined cooling mode will be activated in sequence to supplement the cooling capacity. Peak and peak electricity pricing periods: If the hourly temperature of domestic hot water T < the set target temperature TS: the total heat recovery heat pump unit will be activated first to enter the main heating and secondary cooling mode; if the cooling capacity is insufficient, the ice melting cooling mode, single refrigeration unit cooling mode, heat pump unit simple cooling mode, and dual-condition main unit + ice melting combined cooling mode will be activated in sequence to supplement the cooling capacity; if the hourly temperature of domestic hot water T ≥ the set target temperature TS: the ice melting cooling mode will be activated first according to the user's cooling demand; if the cooling capacity is insufficient, the single refrigeration unit cooling mode, total heat recovery heat pump unit simple cooling mode, heat pump unit simple cooling mode, and dual-condition main unit + ice melting combined cooling mode will be activated in sequence to supplement the cooling capacity.

[0014] Furthermore, the control logic for "transitional season and winter operating conditions" in step S3 includes: During off-peak electricity hours: The dual-mode unit enters ice storage mode; if the hourly temperature of domestic hot water T ≥ the set target temperature TS and the indoor temperature of heating users TN ≥ the set indoor temperature TNS, the single chiller unit starts cooling mode; if T < TS and TN ≥ TNS, and QL < QRS, the total heat recovery heat pump unit starts to recover cooling water for heating + the single chiller unit starts; if QL ≥ QRS, the total heat recovery heat pump unit starts to recover chilled water for primary heating and secondary cooling; if the cooling capacity is insufficient, the single chiller unit starts to supplement the cooling capacity; if T ≥ TS and TN < TNS, and QL < QN, the heat pump unit starts to recover cooling water for heating + the single chiller unit starts; if QL ≥ QN, the heat pump unit starts to recover chilled water for cooling. The chilled water system is used primarily for heating and secondarily for cooling. If the cooling capacity is insufficient, a single refrigeration unit is started to supplement the cooling capacity. If T < TS and TN < TNS, and QL < QRS, the total heat recovery heat pump unit is started to recover cooling water for heating, and the heat pump unit is started to recover cooling water for heating, plus a single refrigeration unit. If QRS ≤ QL < QRS + QN, the total heat recovery heat pump unit is started first to recover chilled water for heating and secondarily for cooling, plus the heat pump unit is started to recover cooling water for heating. If the cooling capacity is insufficient, a single refrigeration unit is started to supplement the cooling capacity. If QL ≥ QRS + QN, the total heat recovery heat pump unit is started first to recover chilled water for heating and secondarily for cooling, plus the heat pump unit is started to recover chilled water for heating and secondarily for cooling. If the cooling capacity is insufficient, a single refrigeration unit is started to supplement the cooling capacity. Off-peak electricity price period: Based on the relationship between T and TS, and between TN and TNS, when T≥TS and TN≥TNS, the single refrigeration unit is preferentially started in the refrigeration mode. If the cooling capacity is insufficient, the full heat recovery heat pump unit is sequentially started in the pure refrigeration mode, the dual-working-condition main unit is started in the refrigeration mode, and the dual-working-condition main unit and ice-melting combined refrigeration mode is started to supplement the cooling capacity; when T<TS and TN≥TNS, the full heat recovery heat pump unit is preferentially operated to recover the heat of chilled water and enter the main heating and auxiliary refrigeration mode. If the cooling capacity is insufficient, the single refrigeration unit is sequentially started in the refrigeration mode, the dual-working-condition main unit is started in the refrigeration mode, and the dual-working-condition main unit and ice-melting combined refrigeration mode is started to supplement the cooling capacity; when T≥TS and TN<TNS, the heat pump unit is preferentially started to recover the heat of chilled water in the main heating and auxiliary refrigeration mode. If the cooling capacity is insufficient, the single refrigeration unit is sequentially started in the refrigeration mode, the full heat recovery heat pump unit is started in the pure refrigeration mode, the dual-working-condition main unit is started in the refrigeration mode, and the dual-working-condition main unit and ice-melting combined refrigeration mode is started to supplement the cooling capacity; when T<TS and TN<TNS, the full heat recovery heat pump unit is preferentially started to recover the heat of chilled water to enter the main heating and auxiliary refrigeration mode plus the heat pump unit recovers the heat of chilled water in the main heating and auxiliary refrigeration mode. If the cooling capacity is insufficient, the single refrigeration unit is sequentially started in the refrigeration mode, the dual-working-condition main unit is started in the refrigeration mode, and the dual-working-condition main unit and ice-melting combined refrigeration mode is started to supplement the cooling capacity; Peak / on-peak electricity price period: Based on the relationship between T and TS, and between TN and TNS, when T≥TS and TN≥TNS, the ice-melting refrigeration mode is preferentially started. If the cooling capacity is insufficient, the single refrigeration unit is sequentially started in the refrigeration mode, the full heat recovery heat pump unit is started in the pure refrigeration mode, the dual-working-condition main unit is started in the refrigeration mode, and the dual-working-condition main unit and ice-melting combined refrigeration mode is started to make up the cooling capacity; when T<TS and TN≥TNS, the full heat recovery heat pump unit is preferentially started to recover the heat of chilled water and enter the main heating and auxiliary refrigeration mode. If the cooling capacity is insufficient, the ice-melting refrigeration mode, the single refrigeration unit refrigeration mode, the dual-working-condition main unit refrigeration mode, and the dual-working-condition main unit and ice-melting combined refrigeration mode are sequentially started to make up the cooling capacity; when T≥TS and TN<TNS, the heat pump unit is preferentially started to recover the heat of chilled water in the main heating and auxiliary refrigeration mode. If the cooling capacity is insufficient, the ice-melting refrigeration mode, the single refrigeration unit refrigeration mode, the full heat recovery heat pump unit pure refrigeration mode, the dual-working-condition main unit refrigeration mode, and the dual-working-condition main unit and ice-melting combined refrigeration mode are sequentially started to make up the cooling capacity; when T<TS and TN<TNS, the full heat recovery heat pump unit is preferentially started to recover the heat of chilled water to enter the main heating and auxiliary refrigeration mode plus the heat pump unit recovers the heat of chilled water in the main heating and auxiliary refrigeration mode. If the cooling capacity is insufficient, the ice-melting refrigeration mode, the single refrigeration unit refrigeration mode, the dual-working-condition main unit refrigeration mode, and the dual-working-condition main unit and ice-melting combined refrigeration mode are sequentially started to make up the cooling capacity.

[0015] The beneficial effects of the present invention are as follows: 1) This multi-mode heat recovery system and its control method have the advantages of a valley-electricity ice storage system composed of a dual-mode host, ethylene glycol pump, ethylene glycol pipe, ice storage device, cooling water circulation pump, cooling water pipe and cooling tower. This reduces the cost of cooling supply and provides recoverable cooling water heat to the heat recovery system during periods of low cooling load demand upstream. This enables the system to realize both a mode of recovering cooling water heat to produce domestic hot water and a mode of recovering cooling water heat for heating, which greatly improves the reliability and economy of the system.

[0016] 2) This multi-mode heat recovery system and its control method possess the advantages of adapting to peak-valley electricity prices in both ice storage mode and central group control system. This allows it to respond to the government's "peak shaving and valley filling" policy, effectively reducing transformer capacity at the enterprise level to decrease distribution capacity fees and utilizing lower off-peak electricity prices to reduce daily electricity costs. Furthermore, it reduces overall transmission and distribution network investment costs at the State Grid level by decreasing transformer capacity at the enterprise level.

[0017] 3) The multi-mode heat recovery system and its control method have the advantages of overcoming the shortcomings of the existing technology, which is that the heat recovery system cannot work continuously and stably due to the intermittent operation of the chilled water and / or cooling water system or the fluctuation of the waste heat end load. It can meet the domestic hot water and / or heating needs of downstream "users" and ensure continuous, stable and efficient operation 24 hours a day throughout the year.

[0018] 4) This multi-mode heat recovery system and its control method have the advantages of being centrally set up as a "regional centralized energy supply system" or "energy station", replacing the traditional decentralized layout in which each equipment unit is set up in different enterprises and relies on pipeline connection. This greatly improves the system's efficiency, significantly reduces the initial investment cost, and greatly improves the convenience of management.

[0019] 5) This multi-mode heat recovery system and its control method can effectively manage regional energy, change the role of "waste heat" energy, realize the flow and distribution of energy among different "users", thereby achieving efficient utilization of regional energy and overall energy saving.

[0020] 6) This multi-mode heat recovery system and its control method can automatically switch working modes, and has the advantages of high efficiency and intelligence. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a flowchart of the control method of the present invention; Figure 3 This is the control logic diagram for off-peak electricity conditions during the summer of this invention; Figure 4 This is the control logic diagram for the summer peak-valley electricity price period of this invention; Figure 5 This is the control logic diagram for peak and high-price periods during summer operating conditions in this invention; Figure 6 This is the control logic diagram for off-peak electricity periods during winter operating conditions of the present invention; Figure 7 This is the control logic diagram for the winter operating conditions and the flat-valley electricity price during the period of this invention; Figure 8 This is the control logic diagram for peak and peak electricity price periods during winter operating conditions in this invention.

[0022] In the diagram: 1. Dual-mode main unit; 2. Ice storage device; 3. Ice melting plate heat exchanger; 4. Single refrigeration unit; 5. Total heat recovery heat pump unit; 6. Heat pump unit; 7. Domestic hot water tank; 8. Cooling tower assembly; 9. Ethylene glycol constant pressure replenishment device; 10. Constant pressure water replenishment device; 11. Ethylene glycol pump; 12. External network ice melting pump; 13. First chilled water circulation pump; 14. Second chilled water circulation pump; 15. Third chilled water circulation pump; 16. Domestic hot water circulation pump; 17. Domestic hot water booster pump; 18. Heating circulation pump; 19. First cooling water circulation pump; 20. Second cooling water circulation pump; 21. Third cooling water circulation pump; 22. Fourth cooling water circulation pump; 23. Valve; 24. Valve; 25. Valve; 26. Valve; 27. Valve; 28. 1. Valves; 29. ​​Valves; 30. Valves; 31. Valves; 32. Valves; 33. Valves; 34. Valves; 35. Valves; 36. Valves; 37. Valves; 38. Valves; 39. Valves; 40. Valves; 41. Valves; 42. Valves; 43. Valves; 44. Valves; 45. Valves; 46. Valves; 47. Valves; 48. Valves; 49. Valves; 50. Valves; 51. Valves; 52. Valves; 53. Ethylene glycol pipes; 54. Chilled water pipes; 55. Heating hot water pipes; 56. Domestic hot water pipes; 57. Domestic hot water heating and circulation pipes; 58. Cooling water pipes; 59. Domestic hot water users who use cooling in summer, heating in winter, and domestic hot water year-round; 60. Users who use cooling year-round; 61. Central group control system; 62. Control cables. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1, by Figure 1This invention provides a multi-mode heat recovery system, comprising a dual-mode main unit 1, an ice storage device 2, an ice-melting plate heat exchanger 3, a single refrigeration unit 4, a total heat recovery heat pump unit 5, a heat pump unit 6, a domestic hot water tank 7, a cooling tower group 8, an ethylene glycol constant pressure replenishment device 9, a constant pressure water replenishment device 10, an ethylene glycol pump 11, an external network ice-melting pump 12, a first chilled water circulation pump 13, a second chilled water circulation pump 14, a third chilled water circulation pump 15, a domestic hot water circulation pump 16, a domestic hot water pressurization pump 17, a heating circulation pump 18, a first cooling water circulation pump 19, a second cooling water circulation pump 20, a third cooling water circulation pump 21, a fourth cooling water circulation pump 22, multiple valves, an ethylene glycol pipe 53, a chilled water pipe 54, a heating hot water pipe 55, a domestic hot water pipe 56, a domestic hot water heating circulation pipe 57, a cooling water pipe 58, a domestic hot water user for summer cooling and winter heating, a domestic hot water user for year-round use 59, a domestic cooling user for year-round use 60, a central group control system 61, and control cables 62. The dual-mode main unit 1, ice storage device 2, and ice melting plate heat exchanger 3 form an ethylene glycol circulation loop through ethylene glycol pipe 53. The single refrigeration unit 4, total heat recovery heat pump unit 5, and heat pump unit 6 form a chilled water circulation loop through chilled water pipe 54 with users who need cooling in summer, heating in winter, and domestic hot water all year round 59 and users who need cooling all year round 60. They also form a cooling water circulation loop through cooling water pipe 58 with cooling tower group 8. The domestic hot water tank 7 is connected to the domestic hot water booster pump 17 and the year-round domestic hot water user 59 via the domestic hot water pipe 56; it is connected to the domestic hot water circulation pump 16 and the total heat recovery heat pump unit 5 via the domestic hot water heating circulation pipe 57, and then back to the domestic hot water tank 7, forming a domestic hot water heating circulation loop. The year-round domestic hot water user 59 is connected to the heating circulation pump 18 and the heat pump unit 6 via the heating hot water pipe 55. The ethylene glycol constant pressure replenishment device 9 is connected to the ethylene glycol pipe 53, and the constant pressure water replenishment device 10 is connected to the chilled water pipe 54; The valves include electric regulating valves, electric switching valves, manual switching valves, and check valves. Multiple valves are respectively installed at the nodes of ethylene glycol pipe 53, chilled water pipe 54, heating hot water pipe 55, domestic hot water pipe 56, domestic hot water heating circulation pipe 57, and cooling water pipe 58. Ethylene glycol pump 11 is installed on ethylene glycol pipe 53, and external network ice melting pump 12 is installed between ice melting plate heat exchanger 3 and chilled water pipe 54. The ethylene glycol side of ice melting plate heat exchanger 3 is connected to ethylene glycol pipe 53, and the chilled water side is connected to chilled water pipe 54. The central group control system 61 is electrically connected via control cables 62 to the dual-mode main unit 1, ice storage device 2, ice melting plate heat exchanger 3, single refrigeration unit 4, total heat recovery heat pump unit 5, heat pump unit 6, cooling tower group 8, ethylene glycol constant pressure replenishment device 9, constant pressure water replenishment device 10, ethylene glycol pump 11, external network ice melting pump 12, first chilled water circulation pump 13, second chilled water circulation pump 14, third chilled water circulation pump 15, domestic hot water circulation pump 16, domestic hot water booster pump 17, heating circulation pump 18, first cooling water circulation pump 19, second cooling water circulation pump 20, third cooling water circulation pump 21, fourth cooling water circulation pump 22, multiple valves 23-52, heat meter, flow meter and various sensors.

[0025] The dual-mode main unit 1, single refrigeration unit 4, and heat pump unit 6 are each equipped with a condenser and an evaporator on their inner side. The total heat recovery heat pump unit 5 is equipped with two condensers and one evaporator on its inner side. The two condensers inside the total heat recovery heat pump unit 5 are independent heat exchange chambers.

[0026] The central group control system 61 can adopt programmable logic control or distributed control system, and the central group control system 61 has an embedded load forecasting model. The load forecasting model is built based on the waste heat load value, downstream user energy demand, outdoor temperature value and real-time electricity price of the day. The central group control system 61 also has a self-learning function, which is used to correct the load forecasting model based on the system's historical operating data.

[0027] The first chilled water circulation pump 13 is installed between the single refrigeration unit 4 and the chilled water pipe 54; the second chilled water circulation pump 14 is installed between the total heat recovery heat pump unit 5 and the chilled water pipe 54; and the third chilled water circulation pump 15 is installed between the heat pump unit 6 and the chilled water pipe 54.

[0028] The outlet of the domestic hot water tank 7 is divided into two paths: one path is connected to the domestic hot water booster pump 17 through the domestic hot water pipe 56, and the outlet of the domestic hot water booster pump 17 is connected to the domestic hot water network of the domestic hot water user 59 who uses cold water in summer and hot water in winter all year round; the other path is connected to the inlet of the domestic hot water circulation pump 16 through the domestic hot water heating circulation pipe 57, forming a domestic hot water heating circulation loop.

[0029] The cooling tower group 8 has a modular structure. Each module of the cooling tower group 8 is connected to the first cooling water circulation pump 19, the second cooling water circulation pump 20, the third cooling water circulation pump 21, and the fourth cooling water circulation pump 22 respectively. Each module is electrically connected to the central group control system 61 through the control cable 62 and can be started and stopped independently.

[0030] This embodiment can be flexibly adjusted according to seasonal changes, peak and off-peak electricity prices, cooling load of upstream users, domestic hot water load and heating load of downstream users, so as to select the optimal operating mode.

[0031] Mode 1: Dual-condition main unit 1 ice storage mode: Valves 23, 25, 26, and 29 are open, and valves 24, 27, and 28 are closed. The corresponding module in cooling tower group 8 starts → the first cooling water circulation pump 19 starts → the ethylene glycol pump 11 starts → the dual-condition main unit 1 starts ice making mode → the ice storage device 2 starts storing ice.

[0032] Mode 2: Dual-condition main unit 1 cooling mode: Valves 23, 24, and 29 are opened, valves 27 and 28 are adjusted, valves 25 and 26 are closed, the corresponding module in cooling tower group 8 starts → the first cooling water circulation pump 19 starts → the external network ice melting pump 12 starts → the ethylene glycol pump 11 starts → the dual-condition main unit 1 starts air conditioning cooling mode.

[0033] Mode 3: Dual-condition main unit 1 + ice melting combined cooling mode: Valves 23, 27, and 29 are opened, valves 24, 25, 28, and 30 are adjusted, valve 26 is closed, the first cooling water circulation pump 19 is started → the external network ice melting pump 12 is started and running → the ethylene glycol pump 11 is started and running → the dual-condition main unit 1 starts the air conditioning cooling mode, and at the same time the ice storage device 2 melts ice for cooling.

[0034] Mode 4: Ice melting and refrigeration mode: Valves 23, 27, and 28 are opened; valves 24, 25, and 30 are adjusted; valve 26 is closed; external network ice melting pump 12 starts running → ethylene glycol pump 11 starts running → ice storage device 2 melts and refrigerates.

[0035] Mode 5: Single refrigeration unit 4 cooling mode: Valves 31 and 32 are opened, the corresponding modules in cooling tower group 8 start → the second cooling water circulation pump 20 starts → the first chilled water circulation pump 13 starts → the single refrigeration unit 4 starts cooling mode.

[0036] Mode 6: Total heat recovery heat pump unit 5 in pure cooling mode: Valves 33, 34, 36, and 38 are opened, and valves 35 and 37 are closed. The corresponding modules in cooling tower group 8 start up → the third cooling water circulation pump 21 starts up → the second chilled water circulation pump 14 starts up → the total heat recovery heat pump unit 5 starts pure cooling mode.

[0037] Mode 7: Total heat recovery heat pump unit 5 recovers heat from cooling water for simple heating mode: Valves 36, 37, and 39 are opened, valve 35 is adjusted, and valves 33, 34, and 38 are closed. Part of the cooling water enters the total heat recovery heat pump unit 5 → domestic hot water circulation pump 16 is started → the total heat recovery heat pump unit 5 starts the simple heating mode.

[0038] Mode 8: Total heat recovery heat pump unit 5 recovers heat from chilled water, main heating and auxiliary cooling mode: valves 33, 36, and 39 are opened, valve 34 is adjusted, and valves 35, 37, and 38 are closed. Domestic hot water circulation pump 16 starts → second chilled water circulation pump 14 starts → total heat recovery heat pump unit 5 starts the main heating and auxiliary cooling mode of total heat recovery operation.

[0039] Mode 9: Heat pump unit 6 in pure cooling mode: Valves 40, 41, 42, and 43 are opened, and valves 44, 45, and 52 are closed. The corresponding module in cooling tower group 8 starts up → the fourth cooling water circulation pump 22 starts up → the third chilled water circulation pump 15 starts up → heat pump unit 6 starts pure cooling mode.

[0040] Mode 10: Heat pump unit 6 recovers heat from cooling water for simple heating mode: valves 44 and 52 are open, valve 45 is adjusted, valves 40, 41, 42, and 43 are closed, and some cooling water enters heat pump unit 6 → heating circulation pump 18 starts → heat pump unit 6 starts simple heating mode.

[0041] Mode 11: Heat pump unit 6 recovers heat from chilled water, main heating and auxiliary cooling mode: valves 42, 43, and 52 are open, valves 40, 41, 44, and 45 are closed, third chilled water circulation pump 15 → heating circulation pump 18 starts → heat pump unit 6 starts operating in main heating and auxiliary cooling mode.

[0042] Example 2, by Figure 2 A control method for a multi-mode heat recovery system is provided, comprising the following steps: S1: The central group control system 61 collects in real time the outdoor ambient temperature TW, the hourly domestic hot water temperature T, the hourly indoor temperature TN of heating users, and the real-time electricity price of the day; and reads the hourly cooling load value QL of upstream cooling users, the hourly domestic hot water load value QRS of downstream users, and the hourly heating load value QN of heating users from the load forecasting model. S2: Based on the real-time data, the central group control system 61 calls the load forecasting model to determine the operating condition that the system should enter: when the continuous 5-day sliding average outdoor temperature is ≥22℃, it enters the summer operating condition; when the continuous 5-day sliding average outdoor temperature is ≤10℃, it enters the winter operating condition; when the continuous 5-day sliding average outdoor temperature is between 10℃ and 22℃, it enters the transitional season operating condition. S3: The central group control system 61 selects the corresponding operating mode and issues control commands based on the current operating conditions and real-time electricity price to control the start-up, shutdown, and opening adjustment of various equipment and valves; S4: During system operation, the central group control system 61 collects actual load data in real time, corrects the operating status of the system, equipment, and valves, or switches modes; at the same time, it enters the actual operating data into the historical database through the "self-learning" function to update the load prediction model.

[0043] In this embodiment, in step S3, the control logic for "summer operating condition" includes: is provided by Figure 3 , during off-peak electricity periods, the dual-working-condition main unit 1 enters the ice storage mode: at this time, according to the user terminal load condition, when T<TS and QL≥QRS, the full heat recovery heat pump unit 5 is preferentially started to recover the chilled water heat, entering the main heating and auxiliary cooling mode. If the user's cooling demand cannot be met at this time, the single cooling unit 4 in the cooling mode and the heat pump unit 6 in the cooling mode are sequentially started as needed to meet the user's cooling demand. When T<TS and QL<QRS, the full heat recovery heat pump unit 5 is started to recover the cooling water heat in the pure heating mode to meet the domestic hot water demand of heating users; at the same time, the single cooling unit 4 in the cooling mode and the heat pump unit 6 in the cooling mode are sequentially started as needed to meet the cooling demand of cooling users. When T≥TS, according to the user's cooling demand, the single cooling unit 4 in the cooling mode is preferentially started, then according to the growth of the cooling load demand of cooling users, the full heat recovery heat pump unit 5 in the pure cooling mode is started, and finally the heat pump unit 6 in the pure cooling mode is started to meet the cooling demand of cooling users.

[0044] is provided by Figure 4 , during flat electricity price periods: when T<TS, the full heat recovery heat pump unit 5 is preferentially started to recover the chilled water heat, entering the main heating and auxiliary cooling mode. If the user's cooling demand cannot be met at this time, the single cooling unit 4 in the cooling mode, the heat pump unit 6 in the pure cooling mode, the dual-working-condition main unit 1 in the cooling mode, and finally the dual-working-condition main unit 1 + ice melting combined cooling mode are sequentially started to meet the cooling demand of cooling users; when T≥TS, according to the user's cooling demand, the single cooling unit 4 in the cooling mode is preferentially started, then according to the growth of load demand, the full heat recovery heat pump unit 5 in the pure cooling mode, the heat pump unit 6 in the pure cooling mode, the dual-working-condition main unit 1 in the cooling mode, and finally the dual-working-condition main unit 1 + ice melting combined cooling mode are sequentially started to meet the cooling demand of cooling users.

[0045] is provided by Figure 5 , during peak and sharp peak electricity price periods: when T<TS, the full heat recovery heat pump unit 5 is preferentially started to recover the chilled water heat, entering the main heating and auxiliary cooling mode. If the user's cooling demand cannot be met at this time, the ice melting cooling mode, the single cooling unit 4 in the cooling mode, the heat pump unit 6 in the pure cooling mode, and finally the dual-working-condition main unit + ice melting combined cooling mode are sequentially started; when T≥TS, according to the user's cooling demand, the ice melting cooling mode is preferentially started, then according to the growth of load demand, the single cooling unit 4 in the cooling mode, the full heat recovery heat pump unit 5 in the pure cooling mode, the heat pump unit 6 in the pure cooling mode, and finally the dual-working-condition main unit 1 + ice melting combined cooling mode are sequentially started to meet the cooling demand of cooling users.

[0046] In step S3, the control logic for "transition seasons and winter" includes: is given by Figure 6 , during off-peak electricity hours, the dual-working-condition main unit 1 enters the ice storage mode; when T≥TS and TN≥TNS, the single refrigeration unit 4 is started in the refrigeration mode to meet the cooling demand of cooling users.

[0047] When T<TS and TN≥TNS, if QL<QRS, the full heat recovery heat pump unit 5 is started in the pure heating mode for recovering cooling water heat to meet the domestic hot water demand of heating users, and at the same time, the single refrigeration unit 4 is started in the refrigeration mode to meet the cooling demand of cooling users; if QL>QRS, the full heat recovery heat pump unit 5 switches to the main heating and auxiliary cooling mode for recovering chilled water heat, so as to provide cooling capacity for cooling users while meeting the domestic hot water demand of heating users. At this time, the refrigeration mode of the single refrigeration unit 4 supplements the insufficient part of the cooling capacity required by cooling users as needed.

[0048] When T≥TS and TN<TNS, if QL<QN, the heat pump unit 6 recovers cooling water heat and enters the pure heating mode to meet the heating demand of heating users, and the single refrigeration unit 4 operates in the refrigeration mode to meet the cooling capacity required by cooling users; but if QL≥QN at this time, the heat pump unit 6 recovers chilled water heat and enters the main heating and auxiliary cooling mode to meet the heating demand of heating users while also providing cooling capacity for cooling users. At this time, the single refrigeration unit 4 starts the refrigeration mode to supplement the insufficient part of the cooling capacity required by cooling users as needed.

[0049] When T<TS and TN<TNS, if the cooling capacity of cooling users is too low, that is, QL<QRS, the full heat recovery heat pump unit 5 is started in the pure heating mode for recovering cooling water heat to meet the domestic hot water demand of heating users; the heat pump unit 6 is started in the pure heating mode for recovering cooling water heat to meet the heating demand of heating users, and at the same time, the single refrigeration unit 4 is started in the refrigeration mode to meet the cooling demand of cooling users; as the cooling load of cooling users increases, that is, QRS<QL<QRS+QN, the full heat recovery heat pump unit 5 switches to the main heating and auxiliary cooling mode for recovering chilled water heat, so as to provide cooling capacity for cooling users while meeting the domestic hot water demand of heating users, the heat pump unit 6 still operates in the pure heating mode for recovering cooling water heat to meet the heating demand of heating users, and the refrigeration mode of the single refrigeration unit 4 supplements the insufficient part of the cooling capacity required by cooling users; as the cooling load of cooling users further increases, that is, QL>QRS+QN, the full heat recovery heat pump unit 5 operates in the main heating and auxiliary cooling mode for recovering chilled water heat, so as to provide cooling capacity for cooling users while meeting the domestic hot water demand of users, the heat pump unit 6 switches to the pure heating mode for recovering chilled water heat to meet the heating demand of heating users while also providing cooling capacity for cooling users. At this time, the refrigeration mode of the single refrigeration unit 4 still supplements the insufficient part of the cooling capacity required by cooling users as needed.

[0050] is given by Figure 7 It is given that, during the off-peak electricity price period: when T≥TS and TN≥TNS, the cooling mode of the single cooling unit 4, the pure cooling mode of the full heat recovery heat pump unit 5, and the cooling mode of the dual-condition main unit 1 are sequentially started as required, and finally the combined cooling mode of dual-condition main unit 1 and ice melting is started to meet the cooling demand of cooling users.

[0051] When T<TS and TN≥TNS, the full heat recovery heat pump unit 5 is prioritized to recover the heat of chilled water to enter the main heating and auxiliary cooling mode, so as to meet the domestic hot water demand of users while providing cooling capacity for cooling users. Then, the cooling mode of the single cooling unit 4 and the cooling mode of the dual-condition main unit 1 are sequentially started as required, and finally the combined cooling mode of dual-condition main unit 1 and ice melting is started to make up for the insufficient part of cooling supply required by cooling users.

[0052] When T≥TS and TN<TNS, the heat pump unit 6 is prioritized to recover the heat of chilled water to enter the main heating and auxiliary cooling mode, so as to meet the heating demand of heating users while also providing cooling capacity for cooling users. Then, the cooling mode of the single cooling unit 4, the pure cooling mode of the full heat recovery heat pump unit 5, and the cooling mode of the dual-condition main unit 1 are sequentially started as required, and finally the combined cooling mode of dual-condition main unit 1 and ice melting is started to make up for the insufficient part of cooling supply required by cooling users.

[0053] When T<TS and TN<TNS, the full heat recovery heat pump unit 5 is prioritized to recover the heat of chilled water to enter the main heating and auxiliary cooling mode, so as to meet the domestic hot water demand of users while providing cooling capacity for cooling users, and the heat pump unit 6 is started to recover the heat of chilled water to enter the main heating and auxiliary cooling mode, so as to meet the heating demand of heating users while also providing cooling capacity for cooling users; then, the cooling mode of the single cooling unit 4 and the cooling mode of the dual-condition main unit 1 are sequentially started as required, and finally the combined cooling mode of dual-condition main unit 1 and ice melting is started to make up for the insufficient part of cooling supply required by cooling users.

[0054] By Figure 8 It is given that, during the peak and critical peak electricity price periods: when T≥TS and TN≥TNS, the ice melting cooling mode, the cooling mode of the single cooling unit 4, the pure cooling mode of the full heat recovery heat pump unit 5, and the cooling mode of the dual-condition main unit 1 are sequentially started as required, and finally the combined cooling mode of dual-condition main unit 1 and ice melting is started to meet the cooling demand of cooling users.

[0055] When T<TS and TN≥TNS, the full heat recovery heat pump unit 5 is prioritized to recover the heat of chilled water to enter the main heating and auxiliary cooling mode. If the cooling demand of users still cannot be met at this time, the ice melting cooling mode, the cooling mode of the single cooling unit 4, and the cooling mode of the dual-condition main unit 1 are started simultaneously in sequence, and finally the combined cooling mode of dual-condition main unit 1 and ice melting is started to make up for the insufficient part of cooling supply required by cooling users.

[0056] When T≥TS and TN<TNS, the heat pump unit 6 is preferentially started to recover the heat of chilled water for the main heating and auxiliary cooling mode. If the user's cooling demand still cannot be met at this time, the ice-melting cooling mode, the cooling mode of the single cooling unit 4, the pure cooling mode of the total heat recovery heat pump unit 5, and the cooling mode of the dual-condition main unit 1 are started in sequence, and finally the combined cooling mode of dual-condition main unit 1 + ice melting is started to make up for the insufficient part of the cooling capacity required by the cooling user.

[0057] When T<TS and TN<TNS, the total heat recovery heat pump unit 5 is preferentially started at the same time to recover the heat of chilled water to enter the main heating and auxiliary cooling mode, and the heat pump unit 6 is started to recover the heat of chilled water for the main heating and auxiliary cooling mode. If the user's cooling demand still cannot be met at this time, the ice-melting cooling mode, the cooling mode of the single cooling unit 4, and the cooling mode of the dual-condition main unit 1 are started in sequence, and finally the combined cooling mode of dual-condition main unit 1 + ice melting is started to make up for the insufficient part of the cooling capacity required by the cooling user.

[0058] Wherein, QL: hourly cooling load of cooling users; QRS: domestic hot water load of heating users; QN: hourly heating load of heating users; Q_ice_storage_release: hourly heat release of the off-peak electricity ice storage system; Q4: rated cooling capacity of the single cooling unit 4; TS: set target temperature of domestic hot water; T: hourly temperature of domestic hot water; TN: indoor temperature of heating users; TNS: set indoor temperature of heating users; To ensure the feasibility of this system, the following basic boundary conditions need to be met at the initial stage of design: the scales of upstream and downstream users shall be matched, for example, one data center cannot be configured to supply domestic hot water for 1000 residential communities 1. During off-peak electricity hours, the maximum value of the sum of the domestic hot water load QRS of heating users and the hourly heating load QN of heating users is less than the minimum value of the sum of the nighttime cooling water heat release Q_ice_storage_release of the ice storage system and the hourly cooling load QL of cooling users in this period, and the rated cooling capacity of the single cooling unit 4 is greater than the maximum value of the hourly cooling load QL of cooling users in this period, that is, max(QRS+QN) ≤ min(Q_ice_storage_release+QL), and Q4>max(QL).

[0059] 2. During flat-valley electricity price periods, critical peak electricity price periods and peak electricity price periods, the maximum value of the sum of the domestic hot water load QRS of heating users and the hourly heating load QN of heating users is less than the minimum value of the hourly cooling load QL of cooling users in this period, that is, max(QRS+QN) ≤ min(QL).

[0060] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0061] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-mode heat recovery system, characterized in that: Includes dual-mode main unit, ice storage device, ice melting plate heat exchanger, single refrigeration unit, total heat recovery heat pump unit, heat pump unit, domestic hot water tank, cooling tower group, ethylene glycol constant pressure replenishment device, constant pressure water replenishment device, ethylene glycol pump, external network ice melting pump, first chilled water circulation pump, second chilled water circulation pump, third chilled water circulation pump, domestic hot water circulation pump, domestic hot water pressurization pump, heating circulation pump, first cooling water circulation pump, second cooling water circulation pump, third cooling water circulation pump, fourth cooling water circulation pump, multiple valves, ethylene glycol pipe, chilled water pipe, heating hot water pipe, domestic hot water pipe, domestic hot water heating circulation pipe, cooling water pipe, users with domestic hot water for summer cooling and winter heating, users with domestic hot water for all year round, users with domestic cooling for all year round, central group control system, control cables; The dual-condition main unit, ice storage device, and ice melting plate heat exchanger form an ethylene glycol circulation loop through ethylene glycol pipes; the single refrigeration unit, total heat recovery heat pump unit, and heat pump unit form a chilled water circulation loop with users who use cooling in summer, heating in winter, and domestic hot water and cooling throughout the year through chilled water pipes, and form a cooling water circulation loop with the cooling tower group through cooling water pipes. The domestic hot water tank is connected to the domestic hot water booster pump via a domestic hot water pipe, and is connected to the domestic hot water circulation pump and the total heat recovery heat pump unit in sequence via a domestic hot water heating circulation pipe, and then back to the domestic hot water tank to form a domestic hot water heating circulation loop. The domestic hot water users who use cold water in summer and heating water in winter and domestic hot water all year round are connected to the heating circulation pump and the heat pump unit via heating hot water pipe. The ethylene glycol constant pressure replenishment device is connected to the ethylene glycol pipe, and the constant pressure water replenishment device is connected to the chilled water pipe; Multiple valves are respectively installed at the nodes of the ethylene glycol pipe, chilled water pipe, heating hot water pipe, domestic hot water pipe, domestic hot water heating circulation pipe, and cooling water pipe; The ethylene glycol pump is installed on the ethylene glycol pipe, and the external network ice-melting pump is installed between the ice-melting plate heat exchanger and the chilled water pipe. The ethylene glycol side of the ice-melting plate heat exchanger is connected to the ethylene glycol pipe, and the chilled water side is connected to the chilled water pipe. The central group control system is electrically connected via control cables to the dual-mode main unit, ice storage device, ice melting plate heat exchanger, single refrigeration unit, total heat recovery heat pump unit, heat pump unit, cooling tower group, ethylene glycol constant pressure replenishment device, constant pressure water replenishment device, ethylene glycol pump, external network ice melting pump, first chilled water circulation pump, second chilled water circulation pump, third chilled water circulation pump, domestic hot water circulation pump, domestic hot water booster pump, heating circulation pump, first cooling water circulation pump, second cooling water circulation pump, third cooling water circulation pump, fourth cooling water circulation pump, multiple valves, heat meter, flow meter and various sensors; The dual-condition main unit, single refrigeration unit, and heat pump unit are each equipped with a condenser and an evaporator on their inner side. The total heat recovery heat pump unit is equipped with two condensers and one evaporator on its inner side. The two condensers on the inner side of the total heat recovery heat pump unit are independent heat exchange chambers. The central group control system adopts programmable logic control or distributed control system, and the central group control system has an embedded load forecasting model. The load forecasting model is built based on the waste heat load value, downstream user energy demand, outdoor temperature value and real-time electricity price of the day. The central group control system also has a self-learning function, which is used to correct the load forecasting model according to the system's historical operating data. The total heat recovery heat pump unit and the heat pump unit have a simple heating mode that recovers heat from cooling water and a mode that recovers heat from chilled water for primary heating and secondary cooling.

2. The multi-mode heat recovery system according to claim 1, characterized in that: The first chilled water circulation pump is installed between the single refrigeration unit and the chilled water pipe; the second chilled water circulation pump is installed between the total heat recovery heat pump unit and the chilled water pipe; and the third chilled water circulation pump is installed between the heat pump unit and the chilled water pipe.

3. The multi-mode heat recovery system according to claim 1, characterized in that: The outlet of the domestic hot water tank is divided into two paths: one path is connected to the domestic hot water booster pump through the domestic hot water pipe, and the outlet of the domestic hot water booster pump is connected to the domestic hot water network of users who need cold water in summer and hot water in winter all year round; the other path is connected to the inlet of the domestic hot water circulation pump through the domestic hot water heating circulation pipe, forming a domestic hot water heating circulation loop.

4. The multi-mode heat recovery system according to claim 1, characterized in that: The cooling tower group has a modular structure. Each module of the cooling tower group is connected to the first cooling water circulation pump, the second cooling water circulation pump, the third cooling water circulation pump, and the fourth cooling water circulation pump. Each module is electrically connected to the central group control system through a control cable and can be started and stopped independently.

5. A control method for a multi-mode heat recovery system according to any one of claims 1-4, characterized in that: Includes the following steps: S1: The central group control system collects outdoor ambient temperature TW, domestic hot water hourly temperature T, heating user indoor hourly temperature TN, and the real-time electricity price of the day in real time; it reads the hourly cooling load value QL of upstream cooling users, the hourly domestic hot water load value QRS of downstream users, and the hourly heating load value QN of downstream users from the load prediction model. S2: The central group control system calls the load prediction model based on real-time data to determine the operating condition that the system should enter: when the sliding average outdoor temperature for 5 consecutive days is ≥22℃, it enters the summer operating condition; When the five-day moving average outdoor temperature is ≤10℃, the system enters winter operating conditions. When the average outdoor temperature for five consecutive days is between 10℃ and 22℃, the system enters the transitional season condition. S3: The central group control system selects the corresponding operating mode and issues control commands based on the current operating conditions and real-time electricity price to control the start-up, shutdown and opening adjustment of various equipment and valves; S4: During system operation, the central group control system collects actual load data in real time, corrects the working status of the system, equipment, and valves, or switches modes; at the same time, it enters the actual operating data into the historical database through the "self-learning" function and updates the load prediction model. The control logic for "summer operating condition" in step S3 includes: During off-peak electricity hours: The dual-mode main unit enters ice storage mode; if the hourly temperature of domestic hot water T < the set target temperature of domestic hot water TS, and the hourly cooling load of the user QL ≥ the downstream user's domestic hot water load QRS: the total heat recovery heat pump unit is started first, and it enters the main heating and secondary cooling mode to recover the heat of chilled water; if this mode cannot meet the user's cooling demand, the single refrigeration unit cooling mode and the heat pump unit cooling mode are started in sequence to supplement the cooling capacity; if the hourly temperature of domestic hot water T < the set target temperature of domestic hot water TS, and the hourly cooling load of the user QL < the downstream user's domestic hot water load QRS: the total heat recovery heat pump unit is started, and it enters the simple heating mode to recover the heat of cooling water; at the same time, according to the user's cooling demand, the single refrigeration unit cooling mode and the heat pump unit cooling mode are started in sequence to supplement the cooling capacity; if the hourly temperature of domestic hot water T ≥ the set target temperature of domestic hot water TS: according to the user's cooling demand, the single refrigeration unit cooling mode is started first, and then according to the increase in cooling load, the total heat recovery heat pump unit simple cooling mode and the heat pump unit simple cooling mode are started in sequence to supplement the cooling capacity. During Pinggu electricity pricing periods: If the hourly temperature of domestic hot water T < the set target temperature TS: the total heat recovery heat pump unit will be activated first to enter the main heating and secondary cooling mode, recovering the heat from the chilled water; if the cooling capacity is insufficient, the single refrigeration unit will be activated in cooling mode, the heat pump unit in simple cooling mode, the dual-condition main unit in cooling mode, and the dual-condition main unit + ice melting combined cooling mode to supplement the cooling capacity in sequence; if the hourly temperature of domestic hot water T ≥ the set target temperature TS: according to the user's cooling demand, the single refrigeration unit will be activated first; if the cooling capacity is insufficient, the total heat recovery heat pump unit in simple cooling mode, the heat pump unit in simple cooling mode, the dual-condition main unit in cooling mode, and the dual-condition main unit + ice melting combined cooling mode will be activated in sequence to supplement the cooling capacity. Peak and peak electricity pricing periods: If the hourly temperature of domestic hot water T < the set target temperature TS: the total heat recovery heat pump unit will be activated first to enter the main heating and secondary cooling mode, recovering the heat from the chilled water; if the cooling capacity is insufficient, the ice-melting cooling mode, single refrigeration unit cooling mode, heat pump unit simple cooling mode, and dual-mode main unit + ice-melting combined cooling mode will be activated in sequence to supplement the cooling capacity; if the hourly temperature of domestic hot water T ≥ the set target temperature TS: the ice-melting cooling mode will be activated first according to the user's cooling demand; if the cooling capacity is insufficient, the single refrigeration unit cooling mode, total heat recovery heat pump unit simple cooling mode, heat pump unit simple cooling mode, and dual-mode main unit + ice-melting combined cooling mode will be activated in sequence to supplement the cooling capacity. The control logic for "transitional season and winter operating conditions" in step S3 includes: Valley electricity period: The dual-working-condition main unit enters the ice storage mode; if the hourly temperature T of domestic hot water ≥ the set target temperature TS of domestic hot water and the indoor temperature TN of heating users ≥ the set indoor temperature TNS of heating users, the single refrigeration unit is started in the refrigeration mode; if T<TS and TN≥TNS, when QL<QRS, the full heat recovery heat pump unit is started to recover the cooling water for heating + the single refrigeration unit, when QL≥QRS, the full heat recovery heat pump unit is started to recover chilled water for main heating and auxiliary refrigeration, and if the cooling capacity is insufficient, the single refrigeration unit is started to make up the cooling capacity; if T≥TS and TN<TNS, when QL<QN, the heat pump unit is started to recover cooling water for heating + the single refrigeration unit, when QL≥QN, the heat pump unit is started to recover chilled water for main heating and auxiliary refrigeration, and if the cooling capacity is insufficient, the single refrigeration unit is started to make up the cooling capacity; if T<TS and TN<TNS, when QL<QRS, the full heat recovery heat pump unit is started to recover cooling water for heating + the heat pump unit is started to recover cooling water for heating + the single refrigeration unit, when QRS≤QL<QRS+QN, the full heat recovery heat pump unit is preferentially started to recover chilled water for main heating and auxiliary refrigeration + the heat pump unit is started to recover cooling water for heating, if the cooling capacity is insufficient, the single refrigeration unit is started to make up the cooling capacity, when QL≥QRS+QN, the full heat recovery heat pump unit is preferentially started to recover chilled water for main heating and auxiliary refrigeration + the heat pump unit is started to recover chilled water for main heating and auxiliary refrigeration, and if the cooling capacity is insufficient, the single refrigeration unit is started to make up the cooling capacity; Flat electricity period: Based on the relationship between T and TS, and TN and TNS, when T≥TS and TN≥TNS, the single refrigeration unit is preferentially started in the refrigeration mode, and if the cooling capacity is insufficient, the full heat recovery heat pump unit in the pure refrigeration mode, the dual-working-condition main unit in the refrigeration mode, and the combined refrigeration mode of dual-working-condition main unit and ice melting are started in sequence to supplement the cooling capacity; when T<TS and TN≥TNS, the full heat recovery heat pump unit is preferentially made to recover the heat of chilled water to enter the main heating and auxiliary refrigeration mode, and if the cooling capacity is insufficient, the single refrigeration unit in the refrigeration mode, the dual-working-condition main unit in the refrigeration mode, and the combined refrigeration mode of dual-working-condition main unit and ice melting are started in sequence to supplement the cooling capacity; when T≥TS and TN<TNS, the heat pump unit is preferentially started to recover the heat of chilled water for the main heating and auxiliary refrigeration mode, and if the cooling capacity is insufficient, the single refrigeration unit in the refrigeration mode, the full heat recovery heat pump unit in the pure refrigeration mode, the dual-working-condition main unit in the refrigeration mode, and the combined refrigeration mode of dual-working-condition main unit and ice melting are started in sequence to supplement the cooling capacity; when T< TS and TN<TNS, the full heat recovery heat pump unit is preferentially started to recover the heat of chilled water to enter the main heating and auxiliary refrigeration mode + the heat pump unit is started to recover the heat of chilled water for the main heating and auxiliary refrigeration mode, and if the cooling capacity is insufficient, the single refrigeration unit in the refrigeration mode, the dual-working-condition main unit in the refrigeration mode, and the combined refrigeration mode of dual-working-condition main unit and ice melting are started in sequence to supplement the cooling capacity; Peak / high electricity price period: Based on the relationship between T and TS, as well as between TN and TNS, when T≥TS and TN≥TNS, the ice-melting refrigeration mode is started preferentially. If the cooling capacity is insufficient, the single refrigeration unit refrigeration mode, the full heat recovery heat pump unit pure refrigeration mode, and the dual-working-condition main unit refrigeration mode are started in sequence, and the dual-working-condition main unit + ice-melting combined refrigeration mode is started to supplement the cooling capacity; when T<TS and TN≥TNS, the full heat recovery heat pump unit is started preferentially to recover the heat of chilled water to enter the main heating and auxiliary refrigeration mode. If the cooling capacity is insufficient, the ice-melting refrigeration mode, the single refrigeration unit refrigeration mode, and the dual-working-condition main unit refrigeration mode are started in sequence, and the dual-working-condition main unit + ice-melting combined refrigeration mode supplements the cooling capacity; when T≥TS and TN<TNS, the heat pump unit is started preferentially to recover the heat of chilled water for the main heating and auxiliary refrigeration mode. If the cooling capacity is insufficient, the ice-melting refrigeration mode, the single refrigeration unit refrigeration mode, the full heat recovery heat pump unit pure refrigeration mode, the dual-working-condition main unit refrigeration mode, and the dual-working-condition main unit + ice-melting combined refrigeration mode are started in sequence to supplement the cooling capacity; when T<TS and TN<TNS, the full heat recovery heat pump unit is started preferentially to recover the heat of chilled water to enter the main heating and auxiliary refrigeration mode + the heat pump unit recovers the heat of chilled water for the main heating and auxiliary refrigeration mode. If the cooling capacity is insufficient, the ice-melting refrigeration mode, the single refrigeration unit refrigeration mode, the dual-working-condition main unit refrigeration mode, and the dual-working-condition main unit + ice-melting combined refrigeration mode are started in sequence to supplement the cooling capacity.

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